The present invention is directed to methods of making agricultural materials from waste paper and other constituents and using them in agricultural applications.
It has been previously proposed to make agricultural materials from waste paper. For example, U.S. Pat. No. 3,269,824 to Aswell discloses the manufacture of soil conditioning and fertilizing pellets from waste paper and fertilizer materials, such as nitrogen, phosphate, potash and calcium. In the Aswell process, the waste paper is macerated and repulped by standard paper regenerating processes. Water is then added and the mixture is pressure cooked into a slurry of finely divided cellulose fibers. The fertilizing materials are then added to the slurry and mixed by mechanical means. The resulting composite is then drained into a vacuum chamber where excess moisture is drawn off until the slurry reaches the consistency of stiff dough. The slurry is then extruded through a die plate having holes therein to form strands of material, which are cut into pellets. Any remaining moisture in the pellets is dried by infra-red lamps.
The Aswell process has a number of disadvantages, a primary one of which is that it requires an unduly large amount of energy. In particular, a substantial amount of energy is consumed by repulping the paper. After the paper is repulped, water is added to the mixture before it is extruded into pellets. The use of a relatively large amount of water, in both the repulping stage and afterward, requires the use of infra-red lamps to dry the pellets after they are formed, which requires additional energy.
As is generally known, plants or crops require that the soil in which they grow have a carbon-to-nitrogen ratio within a particular range, depending upon the plant or crop. For example, a particular plant may require soil having a carbon-to-nitrogen ratio range between 20:1 and 70: 1. If the carbon-to-nitrogen ratio for that plant is substantially greater than the higher boundary, 70:1, then the soil will act as a herbicide because it will draw nitrogen from the plant into the soil, thus gradually killing the plant. The carbon-to-nitrogen ratio of paper is generally about 800:1; therefore, paper that is not supplemented with nitrogen is not suitable as an agricultural material. As used herein, the term "agricultural material" generally refers to any soil supplement, replacement, or alternative used for the purpose of aiding or facilitating the growth of plants or crops. Unlike most plants or crops, mushrooms do not require any specific carbon-to-nitrogen ratio, and may be grown in agricultural materials having high carbon-to-nitrogen ratios, such as ratios in excess of 70:1.
Mushrooms are commercially grown in large quantities in trays having a bottom layer of compost material, which typically includes chicken feces or litter, and a top layer, about two inches thick, which typically includes sphagnum moss, a high-quality peat moss. The mushrooms grow in the top layer, which is called the casing layer. The carbon dioxide emitted by the decomposing compost facilitates the growth of the mushrooms. In order to grow, it is preferable that all areas of the casing layer have a pH that is between about 7 and 9.
Although generally adequate, the growth of mushrooms in conventional trays as described above has a number of disadvantages resulting from the use of sphagnum moss for the casing layer. One disadvantage is the relatively high cost of sphagnum moss. Another disadvantage is that sphagnum moss, which is brown, may discolor the mushrooms when they are harvested, resulting in at least some of the mushrooms having brown spots on them. Consumers may refuse to buy mushroom packages containing mushrooms with brown spots.
An article entitled "Waste Paper as a Substitute for Peat in the Mushroom (Agaricus bisporus) Casing Soil Production" by Dergham, et al. discloses the use of various combinations of waste paper and black peat for use in the casing layers of mushroom trays.
Previously, waste paper and other materials have been converted into pellets for a number of non-agricultural applications, including waste-to-energy conversion systems in which the pellets are utilized as a source of combustion and for use as a hydrophilic material for soaking up spills of liquids such as oil. The manner in which the materials have been pelleted, which is conventional, has included the steps of grinding and/or shredding the material via one or more hammer mills or other devices, utilizing a cyclone, moisturizing the material, providing the material to a pellet mill for pelleting, cooling the pellets, and in some cases crumbling the pellets into smaller pellet fragments.
An article entitled "Recycling Newsprint in Agriculture" by J. H. Edwards discloses, inter alia, the use of a mixture of chicken broiler litter (which includes poultry excreta, feathers, wasted feed, and bedding materials), soil and finely ground newsprint in a number of trenches for growing crops. In one section of the article entitled "Land Application Methods," the author states that "Newsprint should be chopped or ground to furnish a product approximately 0.25 inches in size so that a mulch on the soil surface will not restrict seedling emergence," and that "An alternative method is pelletizing ground newsprint and then applying the pellets to the soil."